A wireless device, in which the orthogonal frequency division multiplexing (OFDM) method and/or a single carrier (SC) frequency division multiple access method has been adopted, utilizes a frequency band formed by bundling plural subcarriers as a unit for wireless communications. The unit is also called “a resource block.”
Since the wireless device performs wireless communications by using the frequency band formed by bundling the plural subcarriers as the unit, it is possible that the wireless device performs wireless communications by utilizing partial subcarriers in an assigned system bandwidth, depending on a traffic volume to be transmitted or quality of communication channels. In other words, the wireless device may perform wireless transmission by using subcarriers included in a portion of the resource blocks included in the system bandwidth, not by utilizing all the subcarriers included in the assigned system bandwidth.
FIGS. 1A and 1B show examples of assigned transmission frequency bands for transmission.
FIG. 1A shows a case in which all the available subcarriers included in the system bandwidth are utilized. FIG. 1B shows a case in which a portion of the subcarriers included in a resource block in the system bandwidth is utilized. Specifically, FIG. 1B shows the case in which the subcarriers included in a specific resource block, among resource blocks included in the system bandwidth, are utilized. Here, the specific resource block is located in a lower frequency range with respect to a center frequency of the system bandwidth. Contrary to this, it is possible that the subcarriers included in another resource block, among the resource blocks included in the system bandwidth, are utilized. Here, other resource block is located in a higher frequency range with respect to the center frequency of the system bandwidth.
By utilizing subcarriers included in a portion of resource blocks included in a system bandwidth, radio resources can be flexibly and efficiently assigned to wireless devices having different QoS requirements or different communication environments.